---
title: "February 20, 2012 Protocol Changes"
shorturl: "feb20"
active: false
banner: ""
date: 2012-02-18
---
<p>
In June 2010 the Bitcoin reference software version 0.2.10 introduced
a change to the protocol: the 'version' messages exchanged by nodes
at connection time would have a new format that included checksum
values to detect corruption by broken networks.
</p><p>
All other messages already carry a checksum (for connections between
nodes 0.2.9 and later) but the version messages themselves could not
be changed in a compatible way, so this change was delayed and did not take effect until
<a href="http://www.timeanddate.com/worldclock/fixedtime.html?msg=Bitcoin+protocol+change&amp;iso=20120220T00">midnight UTC on Feb 20th 2012</a>
to leave users time to upgrade.
</p><p>
The developers of the Bitcoin reference software are unable to find
any evidence of any nodes still running software prior to 0.2.10 on
the network. If any nodes with software this old
do still exist, they will no longer be able to connect to newer nodes.
</p><p>
This switchover has been tested and no significant disruption is
expected and none has been observed so far.
Nodes with incorrect clocks may have a difficult
time making new connections for a brief period around the switchover
time. 
</p><p>
Please report any new connectivity issues to the <a
href="http://webchat.freenode.net/?channels=bitcoin-dev&amp;uio=d4">#bitcoin-dev
channel</a> on Freenode IRC.
</p><p>
If there are unexpected difficulties this page will be updated with
relevant information.
</p>

<div style="text-align:right">
  <i>This notice last updated: Mon, 20 Feb 2012 00:10:00 UTC</i>
</div>
